Conventionally, a vehicle such as an automobile is provided with a positive crankcase ventilation device (PCV device) as a blow-by gas reduction device. The PCV device is configured to return blow-by gas (PCV gas) to an air intake system without emitting the PCV gas to the atmosphere, thereby burning the PCV gas in the engine. The blow-by gas (PCV gas) is discharged through a gap between a piston and a cylinder of an internal combustion engine and emitted from a crankcase. The PCV gas flowing into a crank chamber of the crankcase contains moisture. When engine oil (lubricating oil) in the crank chamber is contaminated with the moisture of PCV gas, the engine oil may be deteriorated. In addition, moisture contained in engine oil and PCV gas may evaporate due to increase in temperature of engine oil accompanied by engine operation. Consequently, pressure in the crank chamber may increase. Thus, operation of the piston may be disturbed.
The PCV device is configured to draw blow-by gas, which is caused in the crankcase, and return the blow-by gas into the intake system, thereby burning the returned blow-by gas in the engine. In addition, the PCV device is further configured to lead pure fresh air, which is filtered by the air cleaner and removed of impurities, into the crankcase, thereby ventilating the crankcase. The PCV device is, in general, configured to return PCV gas to both an intake passage upstream of an throttle valve of an electronic throttle device and an intake passage downstream of the throttle valve so as not draw engine oil. More specifically, the PCV device is, for example, configured to return PCV gas to both an intake passage defined in an air cleaner hose (air hose) and an intake passage in the surge tank or an intake manifold. The air cleaner hose connects the air cleaner with the throttle body.
Generally, PCV gas returned to the intake passage upstream of the throttle valve contains a large amount of moisture or steam. Accordingly, when a PCV hose, a union pipe, or the air hose is cooled, moisture in PCV gas may condense to be condensate. Such condensate drips from an opening of a PCV port into the throttle body, which is located downward in the gravity direction. The condensate may infiltrates into a gap between a shaft and a bearing, and consequently the condensate may cause freezing (icing).